CA2006286A1 - Turbine blade arrival time processor - Google Patents
Turbine blade arrival time processorInfo
- Publication number
- CA2006286A1 CA2006286A1 CA002006286A CA2006286A CA2006286A1 CA 2006286 A1 CA2006286 A1 CA 2006286A1 CA 002006286 A CA002006286 A CA 002006286A CA 2006286 A CA2006286 A CA 2006286A CA 2006286 A1 CA2006286 A1 CA 2006286A1
- Authority
- CA
- Canada
- Prior art keywords
- signal
- producing
- sensor
- blade
- time
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H11/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H1/00—Measuring characteristics of vibrations in solids by using direct conduction to the detector
- G01H1/003—Measuring characteristics of vibrations in solids by using direct conduction to the detector of rotating machines
- G01H1/006—Measuring characteristics of vibrations in solids by using direct conduction to the detector of rotating machines of the rotor of turbo machines
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Control Of Turbines (AREA)
- Transmission And Conversion Of Sensor Element Output (AREA)
- Feedback Control In General (AREA)
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
- Measuring Volume Flow (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An apparatus for detecting turbine blade passing time includes a sensor for producing an input signal each time a blade passes the sensor. Automatic gain control circuitry including a digital multiplier, peak detector and error amplifier regulates the amplitude of the input signal. A zero-crossing detector produces an output signal each time the input signal crosses a reference axis. A
pre-trigger comparator produces a gating signal coinciding with the expected arrival time of the blade at the sensor.
A gating device is responsive to the gating signal for conducting output signals which occur during the expected arrival time of the blade at the sensor. A monostable vibrator produces a digital pulse coinciding with the time at which the blade passes the sensor.
An apparatus for detecting turbine blade passing time includes a sensor for producing an input signal each time a blade passes the sensor. Automatic gain control circuitry including a digital multiplier, peak detector and error amplifier regulates the amplitude of the input signal. A zero-crossing detector produces an output signal each time the input signal crosses a reference axis. A
pre-trigger comparator produces a gating signal coinciding with the expected arrival time of the blade at the sensor.
A gating device is responsive to the gating signal for conducting output signals which occur during the expected arrival time of the blade at the sensor. A monostable vibrator produces a digital pulse coinciding with the time at which the blade passes the sensor.
Description
% 8 ~
1 54,~69 TURBINE B~ADE ARRIVAL TIME PROCESSOR
The present lnvention i~ directed generally to sensors and more particularly to sensors used to detect vibratlons in rotary machines.
Turbine blades, because of their complex design, can suffer from vibration3 at requencie~ which cor~espond to natural ~requencies of the blades called modes. Each mode is associated wlth a di~erent type of vibration such as along the rotational axis o~ the turbin~, perpendicular to the rotati~nal axi~ o~ the turbine, etc. In order to prevent exce~siv~ vlbration of the blade about its normal position, normal design practice dictate~ that the blades be constructed such that these modes are located between harmonics of the operating frequency of the steam turbine.
However, manu~acturing tolerances, changes in blade attachment to the rotor, changes in blade geometry due to erosion and changes in the operating frequency o~ the turbine, among other factors/ cause mode frequ~ncies to approach har~onics o~ the operating frequency.
j2~6 2 5~, ~6g The approach of the mode~ to the harmonics o~ the operatlng ~requency may result in physlcal damage to the steam turbine. When the amplitude of the vibration exceeds a certain level, objectio~able qtresses are set up in the blade. If the condition i~ not dstected and remedied, the blade may eventually fracture resulting in an extremely co~tly forced outage o~ the machinery. Thus, a method for datecting this vibration i5 necegsary in order to prevent such damage.
Historicallyr the vibrational modes of steam turbine blades-have been measured by placing strain gages on the rotating blades and t~leme~ering the info~mation to a stationary receiver. This method ~uffers from three significant drawbacks. First, the strain gage has a very short llfe due to erosion cau ed by steam passing through the turbine blades. Second, each blade requires a strain gaqe i~ all ~lades in a row are to be monitored. Third, the complexity o~ continuously and reliably supplying power to the strain-gage and transmltting the signal reliably from the rotating rotor disk to a stationary receiver creates ~evere dlf~iculties. For these reasons, other types of sensors have been investigated.
The present applic~tion is related to co-pendlng U.S. Application Serlal No. 205,770 entitled APPARATUS FOR
PRECISE DETECTION OF BI,ADE PASSING ~IMES flled June l3, 198 and assigned to the same assignee as the present invention. U.5. Application Serial No. 20S,770 is directed to an apparatu~ for detectlng the passing o~ the blades of a rotatlng machine past a stationary sensox. The sensor produce~ n output signal each time 2 blade passes the sensor. A zero cros ing detector produces an output signal each time the input signal crosses a re erence axis. A
phRse shifter shifts the phase o the input signal to produce a gating signal colnciding with the expected ;~OOG21 36 3 54,~69 arrival time of the blade at the sensor. A gatlng device lg responsive to the gatlng ~ignal for conducting output signals whlch occur durlng the expected arrival time of the blade at the sensor.
The invention disclosed in U.S. Application 205,770 requires that the circuitry be calibrated to operate in conjunction with any partlcular sensor that is used with the apparatus. This calibration is necessary both because of the diffexent characteristic signal amplitudes associated with any particular sensor and because the signal amplitudes al~o depend upon the di~tance between the turbine blade tip and thP surface of the sensor. I~ addition, this apparatus lq sensitive to the frequency of the input signal and thus must be designed for signals o~ any one particular frequency range.
Thus, there is a need for a turbine blade arrival time processor which can compensate automatically for differences in input ~ignal amplitude and i~ not sensitive to input signal frequency.
The prese~t invention ls directed to an apparatus for detecting the passing o~ the turbine blades o~ a rotatlng machine past a stationaxy sen~or. The ~ensor produce~ ~n input signal. ~ach tlme a blade passes the ~ensor. Automatic gain control clrcuitry regulates the amplitude o~ the input signal. The auto~atic yain control clrcuitry includes a digltal multiplier, a pea~ detector and an error amplifler. A zero-crossing detector produces an output signal each time the input ~ignaL crosses a reference axis~ A pre-trigger comparator produces a gating signal coinciding with the expected arrival tlme of the blade at the sensor. A gating device is responsive to the gating signal for conductlng output signals which occur during the expected arrival time o~ the blade at the 54, g69 sensor. A monostable vibrator produces a digital pulse coinciding with the time at which the blade passes the sensor.
The present invention is also directed to a method of detectlng the passing of the blades of a rotating machln~ past a statlonary sensor. The method includes the step of producing an input signal each time a blade passes a stationary sensor. The amplltude of the input signal is regulatedO An output signal is produced each time the input slgnal crosses a reference axis. A gatlng signal is produced which coincides with the expected arrival time of the blade at the sensor. The output signal is selectively conducted in response to the gating slgnal. A digital pulse is produced which colncides with the time at which a blade passes th~ sensor.
Th~ present invention incorporates the features of automatic galn control for the input ~lgnal and means for dlgitally producing a '~ki~e of arrival" ~ignal which is independent of the ~requency of the input signal~ These and other advantages and benefits of the pres~nt invention will become apparent from a description o~ a pre~erred embodiment hereinbalow.
In order that the present inventio~ may be clearly understood and readlly practiced, a preferred embodimsnt wlll now be described, by way of example only~
with re~erence to the accompanying figure~ whereln:
FIG. 1 illustrates a circuit constructed according to the teaching~ of the present invention for processing the ~ignals produced by a magnetic sensor;
FIGSo 2A-~G illustrate the plots of various signals useful ln explaining the operation of the circuit shown i~ F~G. l; and FIG~ 3 illustrates a typical magnetic sensor.
8~ ~
54,q69 FIG~ 1 illu~trate-~ a Qimplified circuit diagram for an apparatus 10 as~ociated with a turbine blade arrival time proce~sor of th~ present inventiona The apparatus 10 functlons to automatically regulate khe amplitude o~ input signals and th~n to proc2ss these regulated input signals in order to discern the ~ime at whlch a "turbln2 blade arrival" e~ent occurs. Automatic gain control clrcuitry which functions to regulate the amplitude of the input signals is shown inside the dotted llnes o~ FI~. 1 whil~
signal processing circuitry is shown outslde o the dotted lines.
A signal generated by a magnetic sensor 50, such as shown in FIG. 3, 15 lnput acro~ an inverting and a noninverting input terminal o~ a di~ferential amplifler 12.
One type of differential ampliflar which may be used in the apparatus 10 of this inventlon ls component INA117 available from Burr-Brown Corporation. An impedance matchlng resistor 14 i8 al~o connected across the inverting and noninverting input~ o~ differential ampli~ier 12. A
voltage ~ignal VA is available at an output terminal o~ tlle differ~ntial amplifier 12.
Voltage ~ig~al VA is lnput to a noninverting input of operatlonal ampli~ier 16 throu~h the RC network con~i~ting o~ capacitors 15, 46 and ~7 and re~lstors 48 and 49, The capacitors 15, 46 and 4? are connected ln ~eries between the output terminal of the dl~ferential amplifl~r 1Z and the noninver~ing inpu of operational amplifier 160 Re~istor 48 is connected from the anode of capacitor 47 to ground whlle resistor 49 is connected from the cathode of capacitor 15 to ground~ An output terminal of operational amplifier 16 is connected to an inverting input of operational amplifier 16 and ls also ~onnected through resistor 17 to an anode of capacltor 15~ Operational 6 5~,4~g ampll~Ler 16 functions as a hlgh-pa~s filter to re~ect a~y 60 Hz component~ whlch may be coupled ~o khe input slgnal.
The hlgh-pass filter 16 can be either closed into the circuit or removed from the circ~it by moving switch 18 to the appropriate positlon. One type of operational amplifier which may be used for the high-pass filter 16 is component LF347 available from National S~miconductor.
A voltage signal avallable at an output of the high-pass filter 16 is input to either a Y1 or a Y~ input of a multiplier 1g by positioning a switch 20 in the proper position. The use of the switch 20 to route the ouput signal of high-pass filter 16 to either the Y1 or the Y2 input terminal of multiplier 19 provides the capability of inverting the input signal and is a convenient method of effectively changing the polarity of sensor 50 without the need for rewiring. Input X1 Qf multlplier 19 is connected to an output terminal of buffer 29 while input terminal X2 is con~ected to ground. One type of multiplier 19 which may be used in the apparatus 10 o~ this invention is componerlt AD532 available from Analog Device~
A voltage signal avallable at an output terminal of multiplier 19 is input through resistor 2Z to an inverting lnput of operatlonal amplif:Ler 21~ A
noninvertiny input of operational ampli~ier 21 is conrlected to ground while an ouput terminal of operational ampllfler 21 19 connected thro~gh re~i~tsr 23 to the inverting lnput of operational ampli~ier 27. Operational amplifiex 21 acts as an lnverting amplifier and through the proper ~ele~tion o~ resi~tors 22 and ~3 may exhibit a gain o~ 20. One type of operatlonal amplifier which may be used for inverting amplifier 21 in the apparatus 10 of thls invention is component LF347. A voltage signal VB ls available at an output terminal of inverting amplifier 21.
~2~
7 54,469 Voltage signal VB i~ input to an inve~ting input of comparator 24 which is de~lgned to act as ~ peak detector. A noninverting input of comparator 24 is connected through xesistor 62 to ground. The noninverting input of comparator 24 is also connected to both an inverting output of comparator 24 and through capacitor 63 to groundO One type o~ device whlch may be u ed for the pea~ detector 24 is component hM311 available ~rom National Semiconductor.
An inverted output signal of peak detector 24 is input to a noninverting input of operational amplifier 25 which acts as a buffer. An ouput terminal of operational amplifier 25 is connected to an inverting input of operational amplifier 25. Component LF347 is one type oP
operational amplifier whlch may be used for buffer 250 A
voltage signal Vc is available at an output terminal of buffer 25.
Voltage signal V~ is input through resistor 27 to an inverting input of an operational ampli~ler 26 which acts as an error amplifier. A noninverting input of operational amplifier 26 is connected to a reference voltage VR o~, ~or example, ~5 volts DC. An ouput o~
operational ampli~ier 26 i.~ connected through r~ istor 28 to the inver~ing input of operational ampllPler 26. Error amplifier 26 may exhibit a gain o~ 20 through the proper selection of resistors 27 and 2a. One type o~ device which may be u~ed for error ampli~ier 26 i~ component LF347.
A signal available at the output of the error amplifier 2~ is input to a noninverting input of operational ampllier 29 which acts as a buffer. An ouput terminal of operat~onal amplifier 29 is connected to an inverting input of operational amplifier 29. A voltage .7 8 5~,469 signal VD available at an output o huf~er 29 i~ input to the X1 terminal o~ multiplier 19. One type of devlce which may be used for buffer 29 i component LF347~
Voltage slgnal V3 avallable a~ the ouput of inverting ampllfier 21 is lnput to a noninverting input of operational amplifier 30 which acts as a buffer. An output terminal of operatlonal amplifier 30 i5 connected to an inverting input of operational amplifier 30. A voltage signal available at the output terminal of operatlonal amplifler 30 is input to an R-L-C networ~ consisting of resistor 31, inductor 32 and capacitor 33. This R-L-C
network is likewise connected to a noninverting input of operational ampllfier 34 which acts as a buf~er. An output terminal of operational amplifier 34 i5 connected to an inverting input of operational amplifier 34. The series combination of the R-L C network and buffer 34 ~unctions as a low-pass ~ilter to reduce htgh-frequenc~ noiqe.
Component LF347 may be used for both buffers 30 and 34.
Volt~ge signal VB is also input to the noninverting input of operational amplifier 44 which acts as a bu~fer. An output termlnal of operational amplifier 44 i~ c~nnected to an inverting lnput o~ operatlonal ampli~ier 44. Voltage slgnal V~ i5 available for monitorlng at an output terminal o~ bu~er device 44.
Component LF347 may be used for huf~er device 44.
-- A voltage signal VE available at an output terminal of buf~er 34 1~ input to inverting .tnputs of both comparators 3S and 36. Comparator 35 ~unct.tons as a pre-trlqger comparator while comparator 36 functions as a zero-crossing comparator. A noninverting input of comparator 35 i~ con~ected to a reference voltage VR of, for exampl~, ~142 volts DC. A noninvertlng input o~
comparator 36 is connected to a reference voltage VR of, for example, ~0.12 volts DC. Voltage comparator device 9 54,469 LM360 available from National Semiconductor may bs used ~or both pre-~rlgger comparator 35 and zero-crossing comparator 36 .
A voltage signal VF available at an output terminal of pre-trlgger comparator 35 ls input to a clock input terminal o~ pr~-trigger ~lip flop 38. Device 74LS74A
available ~rom Texas Instrum~nts may be used for pre-trlgger flip-flop 38. Both a preset ~erminal and a ~
te~minal of pre-trigger fllp-flop 38 are tied to l5 volts DCo A voltage signal VG available at a Q output of pre-trigger flip-flop ~8 is an input to NA~D gate 40. Device 74LS00 available from Texas Instruments may be used for NAND gate 40. A voltage slgnal VH available at an ouput terminal of zero-crossing comparator 36 is a second input to NAND gate 40.
A voltage signal VI available at an output of NAND gate 40 is input to an ~ input of monostable ~2.
Device 74LS221 available from Texas Instruments may be used for monostable 4~. ~oth a clear input and a B input of monostable 42 are tied ~o +5 volts DC. A voltage signal VK
available at a Q output o mono~table 42 ~s input to a clear termlnal of pre-trlgg~r ~llp~flop 3~. A capacltor 41 is connected in parallel to CEX and RCEX terminal~ o~
monostAble 42 while reslstor 43 i~ connected between ~he RC~X torminal oP monostable 42 and a v~altage source o~ ~5 volts DCo A voltage signal VJ i3 available at a Q output of monostable 42.
In operation, the filtered ihpUt signal VA is input to automatic gain control clrcuitry shown within the dotted lines of FIG. 1 which consists of multiplier 19, invert~ng amplifier 21, peak detector 24, buffers 25 and 29 and error amplifier 26~ The automatic gain control circuitry functions to regulate the amplitude of voltage signal VB at a nominal 10 volt peak-to-peak level.
54,q69 Analy~ls shows that the automatic gain control circuitry exhibits a transfer function which can be represented hy the fol1owing equation: .
IVBI ~ (1 B) VR ~ _ ) ~here IVBI ab~olute value o~ the pea~ value of voltage signal VB;
Al absolute value of the peak value of voltage signal VA;
= dimensionles~ ratio of th~ resistance . values in ohms of resistor 23 to resistor 22;
= dime~sionless ratio of the reslstanoe values i~ ohms of resistor 28 to re~istor 27;
VR a re~erence voltage at th~ noninverting input of error amplifier 2~.
~ y way o~ ~xample o~ the operakion of the automatic gain control circuitry, let ~ 20 anc~ ].et V~
~ ~S volt~ DC~ The ahove equation can be 3impli~ied a~
follow~:
IVal ~ S.2S ~ IVAI
~I--V I , 0 0 2 S J
For IVAI ~ 0.025 VO1tS~ IVBI is vexy nearly equal to 5.~5 volts. For example, if IVAI = 1 volt, then IVBI - 5O122 volts; if IVAI - 10 volts, then IV~7 - SO2369 volts. The preceding example d2monstrates that the amplitude of the voltage VB remains within 2.5~ of $.25 volts for a 10:1 variation in the amplitude of VA.
11 5~,~69 The voltage signal V~ is then bu~ered by device 30 and input to a low-pas ilter to reduce hlgh-Erequency noiseO The resulting voltage signal VE ls illugtrated in FIG. 2A. Voltage signal V~ i8 then compare~ by pre-trigger comparator 35 to a positive reference voltage of, ~or example, +1.2 volts DC. The voltage signal VF at the inverted ouput terminal of pre-trigger comparator 35 corresponds to a logic level "1" when~Yer voltage signal VE
is greater than 1.2 volts. Voltag~ signal VF i5 illustrated in FIG. 2B.
Voltage signal VF s~rves as the clock input to positive-edge triggered flip-flop 38. The ~ inp~t and preset input are both alway~ tied to a loglc "1" level.
When voltag~ signal VF goes "high~" the Q outplu~ o~ flip-flop 38 (voltag~ signal VG) also goes "high." The slight delay between the rising edges of th~se signals corresponds to the propagation delay o~ flip-flop 38. Voltage signal VG is illustrated in ~I~. 2C.
Voltage signal VE i5 also i~put to zero-crossing comparator 36 where lt is compared to a negative reference voltage of, ~or example, -0.12 voltc DC. The voltage signal VH at the output terminal o~ zero-crossing detector 36 corre~ponds to a logic level "1" whenever voltage signal VE is les3 than -0.12 volt~. Voltage signal VN is illustrated in FIG~ ~D.
The voltage ~lgnal VI goes "low" wh-3never both lnputs VG and VH are at the loglc "1" level. Voltage signal V~ i~ illustrated in FIG. 2E~ The falling edge o~
voltage signal VI which is input to the ~ termlnal of monostable 42 causes the Q output of monostable 42 (vcltage signal v,~) to go "high" and th~ Q output (voltage signal VK) to go "low. " The width o~ these signals VJ and VK is approximately equal to .7U secr Thi~ pulse width is ~OC3G~6 12 54,469 determined by the Yalues of capacitor 41 and resistor ~3.
Voltage signals VJ and VK are illustrated in FIG5. 2F and 2G, respectively.
The voltage signal VJ is input to processing circuitry ~not shown) for determining turblne blade vibratlon in a known manner. The voltage signal V~ is input to the c].ear terminal o~ ~lip-10p 38 to cause voltage signal VG to return to a logic "0" level.
The design o ths circuit 10 of the present invention prevents the erratic triggering of the "time of arrival" pulse VJ due to varlatlons in input signal VA
amplitude and the presence of noi~e on the input signal VA.
First, the automatic gain control circuitry prevlously described regulates the amplitude of voltage signal VE at a nominal peak to-peak value. Second, the rising edge of voltage slgnal VH (the ri~ing edge o~ Yoltage signal VH
corresponds to the tlme that voltage signal VE crosses the reference voltage of -0.12 volts when voltage signal VE is decreaslng in value whlch ln turn corresponds to the time at which a turbine blade passes magnetic sensor S0) ls only permitted to trlgger mono~table 42 ln order to produce the pul~e on voltage ignal VJ when voltage signal ~ i9 at a logic "1" level. Voltage slgnal VG goes to a logic "1"
level only when voltage si~nal V~ cro~se~ the ~1~2 volt re~erence axis at a time when voltage ~ignal V~ i9 increasing in valueO Thus~ the clrcuit 10 of the present lnventlon anticipates the tlme when voltage slgnal VE will cross the -0.12 volt re~erenc~ axis in response to a turbine blade passing the magnetlc sensor S0 by first detectlng the positive portion o~ the ~inusoid of voltage signal Y~. Any noise which erratically causes voltage signal YE to cross the -0 . 1 2 Yolt reference axis will not, thus, erroneously produce a pulse on voltage signal VJ and provide incorrect turbine blade "time o axrival" dataO
~62~f~
1 3 5~, 469 The circuit lO of the present inventlon l~ also designed such that its operatlon i not sensitive to the frequency o~ the input slgnal VA. The voltage slgnal V
produced by flip-flop 38 which antlclpates the "tlme of arrival" of a turbine blade at the magnetic sensor 50, is trigg~red when voltage signal VE crosses tha ~1.2 volt reference axis at a time when voltage ~igna} VE i5 increaslng ln Yalue and i9 entlrely lndependent of the frequency of the ~nput signal VA, A sensor 50 which can be used in combination with the circult lo of FIG. 1 is illustrated ln FIG. 3~ The magnetic sensor 50 is a self-generating, vaxiable-reluctance transducer which does not require a power supply. Su~h sensor^q are often used ~or measur1ng rotational speed by counting the teeth on a gear~
Appropriate sensors are commercially available and can be obtained in a variety of con~iguratioQs and package designs for particular appllcations.
The sensors used in combinatlon with the present invention, have, for example, a very high strength magnet 52. The sensor housing 54 may be machlned ~rom a single piece of ~talnless steel bar stock, whlch i9 enclosed by EB
weldlng to special hermetically seale~ connectors 56. The magnet 52 operate~ in con~unction wlth a pole piece 5~. A
pick~up coil 60 pro~uces a signal which i3 conducted hy slgnal wlres to the diP~e~entlal amplif~er 12 o~ FIG. l.
~ The lnternals o~ the sensor 50 should be suitable ~or operation at 550 E (287.8 C). Such sensors can be obtained from Ai~pax, a division vf North American Phillips or Electro-Products. The mountlng o~ sensors, such as sensor 5Q, in a turbomachlne ls well known. See ~or example V.s. Patent No. 4,573,3S8 issued ~arch ~, 1986 to Luongo~ Sensor to surface distances may vary ~etween 15Q
to 250 mils (.0381 to .Q635 mm).
~D06Z86 14 54,~69 Whlle the pre.~ent invention has been described in connectlon with an exemplary embodiment thereof, it will be understood that many modifications and variations will be readily apparent to those of ordinary skill in the art.
This disclosure and the following claims are intended to cover all such modifications and variations.
1 54,~69 TURBINE B~ADE ARRIVAL TIME PROCESSOR
The present lnvention i~ directed generally to sensors and more particularly to sensors used to detect vibratlons in rotary machines.
Turbine blades, because of their complex design, can suffer from vibration3 at requencie~ which cor~espond to natural ~requencies of the blades called modes. Each mode is associated wlth a di~erent type of vibration such as along the rotational axis o~ the turbin~, perpendicular to the rotati~nal axi~ o~ the turbine, etc. In order to prevent exce~siv~ vlbration of the blade about its normal position, normal design practice dictate~ that the blades be constructed such that these modes are located between harmonics of the operating frequency of the steam turbine.
However, manu~acturing tolerances, changes in blade attachment to the rotor, changes in blade geometry due to erosion and changes in the operating frequency o~ the turbine, among other factors/ cause mode frequ~ncies to approach har~onics o~ the operating frequency.
j2~6 2 5~, ~6g The approach of the mode~ to the harmonics o~ the operatlng ~requency may result in physlcal damage to the steam turbine. When the amplitude of the vibration exceeds a certain level, objectio~able qtresses are set up in the blade. If the condition i~ not dstected and remedied, the blade may eventually fracture resulting in an extremely co~tly forced outage o~ the machinery. Thus, a method for datecting this vibration i5 necegsary in order to prevent such damage.
Historicallyr the vibrational modes of steam turbine blades-have been measured by placing strain gages on the rotating blades and t~leme~ering the info~mation to a stationary receiver. This method ~uffers from three significant drawbacks. First, the strain gage has a very short llfe due to erosion cau ed by steam passing through the turbine blades. Second, each blade requires a strain gaqe i~ all ~lades in a row are to be monitored. Third, the complexity o~ continuously and reliably supplying power to the strain-gage and transmltting the signal reliably from the rotating rotor disk to a stationary receiver creates ~evere dlf~iculties. For these reasons, other types of sensors have been investigated.
The present applic~tion is related to co-pendlng U.S. Application Serlal No. 205,770 entitled APPARATUS FOR
PRECISE DETECTION OF BI,ADE PASSING ~IMES flled June l3, 198 and assigned to the same assignee as the present invention. U.5. Application Serial No. 20S,770 is directed to an apparatu~ for detectlng the passing o~ the blades of a rotatlng machine past a stationary sensox. The sensor produce~ n output signal each time 2 blade passes the sensor. A zero cros ing detector produces an output signal each time the input signal crosses a re erence axis. A
phRse shifter shifts the phase o the input signal to produce a gating signal colnciding with the expected ;~OOG21 36 3 54,~69 arrival time of the blade at the sensor. A gatlng device lg responsive to the gatlng ~ignal for conducting output signals whlch occur durlng the expected arrival time of the blade at the sensor.
The invention disclosed in U.S. Application 205,770 requires that the circuitry be calibrated to operate in conjunction with any partlcular sensor that is used with the apparatus. This calibration is necessary both because of the diffexent characteristic signal amplitudes associated with any particular sensor and because the signal amplitudes al~o depend upon the di~tance between the turbine blade tip and thP surface of the sensor. I~ addition, this apparatus lq sensitive to the frequency of the input signal and thus must be designed for signals o~ any one particular frequency range.
Thus, there is a need for a turbine blade arrival time processor which can compensate automatically for differences in input ~ignal amplitude and i~ not sensitive to input signal frequency.
The prese~t invention ls directed to an apparatus for detecting the passing o~ the turbine blades o~ a rotatlng machine past a stationaxy sen~or. The ~ensor produce~ ~n input signal. ~ach tlme a blade passes the ~ensor. Automatic gain control clrcuitry regulates the amplitude o~ the input signal. The auto~atic yain control clrcuitry includes a digltal multiplier, a pea~ detector and an error amplifler. A zero-crossing detector produces an output signal each time the input ~ignaL crosses a reference axis~ A pre-trigger comparator produces a gating signal coinciding with the expected arrival tlme of the blade at the sensor. A gating device is responsive to the gating signal for conductlng output signals which occur during the expected arrival time o~ the blade at the 54, g69 sensor. A monostable vibrator produces a digital pulse coinciding with the time at which the blade passes the sensor.
The present invention is also directed to a method of detectlng the passing of the blades of a rotating machln~ past a statlonary sensor. The method includes the step of producing an input signal each time a blade passes a stationary sensor. The amplltude of the input signal is regulatedO An output signal is produced each time the input slgnal crosses a reference axis. A gatlng signal is produced which coincides with the expected arrival time of the blade at the sensor. The output signal is selectively conducted in response to the gating slgnal. A digital pulse is produced which colncides with the time at which a blade passes th~ sensor.
Th~ present invention incorporates the features of automatic galn control for the input ~lgnal and means for dlgitally producing a '~ki~e of arrival" ~ignal which is independent of the ~requency of the input signal~ These and other advantages and benefits of the pres~nt invention will become apparent from a description o~ a pre~erred embodiment hereinbalow.
In order that the present inventio~ may be clearly understood and readlly practiced, a preferred embodimsnt wlll now be described, by way of example only~
with re~erence to the accompanying figure~ whereln:
FIG. 1 illustrates a circuit constructed according to the teaching~ of the present invention for processing the ~ignals produced by a magnetic sensor;
FIGSo 2A-~G illustrate the plots of various signals useful ln explaining the operation of the circuit shown i~ F~G. l; and FIG~ 3 illustrates a typical magnetic sensor.
8~ ~
54,q69 FIG~ 1 illu~trate-~ a Qimplified circuit diagram for an apparatus 10 as~ociated with a turbine blade arrival time proce~sor of th~ present inventiona The apparatus 10 functlons to automatically regulate khe amplitude o~ input signals and th~n to proc2ss these regulated input signals in order to discern the ~ime at whlch a "turbln2 blade arrival" e~ent occurs. Automatic gain control clrcuitry which functions to regulate the amplitude of the input signals is shown inside the dotted llnes o~ FI~. 1 whil~
signal processing circuitry is shown outslde o the dotted lines.
A signal generated by a magnetic sensor 50, such as shown in FIG. 3, 15 lnput acro~ an inverting and a noninverting input terminal o~ a di~ferential amplifler 12.
One type of differential ampliflar which may be used in the apparatus 10 of this inventlon ls component INA117 available from Burr-Brown Corporation. An impedance matchlng resistor 14 i8 al~o connected across the inverting and noninverting input~ o~ differential ampli~ier 12. A
voltage ~ignal VA is available at an output terminal o~ tlle differ~ntial amplifier 12.
Voltage ~ig~al VA is lnput to a noninverting input of operatlonal ampli~ier 16 throu~h the RC network con~i~ting o~ capacitors 15, 46 and ~7 and re~lstors 48 and 49, The capacitors 15, 46 and 4? are connected ln ~eries between the output terminal of the dl~ferential amplifl~r 1Z and the noninver~ing inpu of operational amplifier 160 Re~istor 48 is connected from the anode of capacitor 47 to ground whlle resistor 49 is connected from the cathode of capacitor 15 to ground~ An output terminal of operational amplifier 16 is connected to an inverting input of operational amplifier 16 and ls also ~onnected through resistor 17 to an anode of capacltor 15~ Operational 6 5~,4~g ampll~Ler 16 functions as a hlgh-pa~s filter to re~ect a~y 60 Hz component~ whlch may be coupled ~o khe input slgnal.
The hlgh-pass filter 16 can be either closed into the circuit or removed from the circ~it by moving switch 18 to the appropriate positlon. One type of operational amplifier which may be used for the high-pass filter 16 is component LF347 available from National S~miconductor.
A voltage signal avallable at an output of the high-pass filter 16 is input to either a Y1 or a Y~ input of a multiplier 1g by positioning a switch 20 in the proper position. The use of the switch 20 to route the ouput signal of high-pass filter 16 to either the Y1 or the Y2 input terminal of multiplier 19 provides the capability of inverting the input signal and is a convenient method of effectively changing the polarity of sensor 50 without the need for rewiring. Input X1 Qf multlplier 19 is connected to an output terminal of buffer 29 while input terminal X2 is con~ected to ground. One type of multiplier 19 which may be used in the apparatus 10 o~ this invention is componerlt AD532 available from Analog Device~
A voltage signal avallable at an output terminal of multiplier 19 is input through resistor 2Z to an inverting lnput of operatlonal amplif:Ler 21~ A
noninvertiny input of operational ampli~ier 21 is conrlected to ground while an ouput terminal of operational ampllfler 21 19 connected thro~gh re~i~tsr 23 to the inverting lnput of operational ampli~ier 27. Operational amplifiex 21 acts as an lnverting amplifier and through the proper ~ele~tion o~ resi~tors 22 and ~3 may exhibit a gain o~ 20. One type of operatlonal amplifier which may be used for inverting amplifier 21 in the apparatus 10 of thls invention is component LF347. A voltage signal VB ls available at an output terminal of inverting amplifier 21.
~2~
7 54,469 Voltage signal VB i~ input to an inve~ting input of comparator 24 which is de~lgned to act as ~ peak detector. A noninverting input of comparator 24 is connected through xesistor 62 to ground. The noninverting input of comparator 24 is also connected to both an inverting output of comparator 24 and through capacitor 63 to groundO One type o~ device whlch may be u ed for the pea~ detector 24 is component hM311 available ~rom National Semiconductor.
An inverted output signal of peak detector 24 is input to a noninverting input of operational amplifier 25 which acts as a buffer. An ouput terminal of operational amplifier 25 is connected to an inverting input of operational amplifier 25. Component LF347 is one type oP
operational amplifier whlch may be used for buffer 250 A
voltage signal Vc is available at an output terminal of buffer 25.
Voltage signal V~ is input through resistor 27 to an inverting input of an operational ampli~ler 26 which acts as an error amplifier. A noninverting input of operational amplifier 26 is connected to a reference voltage VR o~, ~or example, ~5 volts DC. An ouput o~
operational ampli~ier 26 i.~ connected through r~ istor 28 to the inver~ing input of operational ampllPler 26. Error amplifier 26 may exhibit a gain o~ 20 through the proper selection of resistors 27 and 2a. One type o~ device which may be u~ed for error ampli~ier 26 i~ component LF347.
A signal available at the output of the error amplifier 2~ is input to a noninverting input of operational ampllier 29 which acts as a buffer. An ouput terminal of operat~onal amplifier 29 is connected to an inverting input of operational amplifier 29. A voltage .7 8 5~,469 signal VD available at an output o huf~er 29 i~ input to the X1 terminal o~ multiplier 19. One type of devlce which may be used for buffer 29 i component LF347~
Voltage slgnal V3 avallable a~ the ouput of inverting ampllfier 21 is lnput to a noninverting input of operational amplifier 30 which acts as a buffer. An output terminal of operatlonal amplifier 30 i5 connected to an inverting input of operational amplifier 30. A voltage signal available at the output terminal of operatlonal amplifler 30 is input to an R-L-C networ~ consisting of resistor 31, inductor 32 and capacitor 33. This R-L-C
network is likewise connected to a noninverting input of operational ampllfier 34 which acts as a buf~er. An output terminal of operational amplifier 34 i5 connected to an inverting input of operational amplifier 34. The series combination of the R-L C network and buffer 34 ~unctions as a low-pass ~ilter to reduce htgh-frequenc~ noiqe.
Component LF347 may be used for both buffers 30 and 34.
Volt~ge signal VB is also input to the noninverting input of operational amplifier 44 which acts as a bu~fer. An output termlnal of operational amplifier 44 i~ c~nnected to an inverting lnput o~ operatlonal ampli~ier 44. Voltage slgnal V~ i5 available for monitorlng at an output terminal o~ bu~er device 44.
Component LF347 may be used for huf~er device 44.
-- A voltage signal VE available at an output terminal of buf~er 34 1~ input to inverting .tnputs of both comparators 3S and 36. Comparator 35 ~unct.tons as a pre-trlqger comparator while comparator 36 functions as a zero-crossing comparator. A noninverting input of comparator 35 i~ con~ected to a reference voltage VR of, for exampl~, ~142 volts DC. A noninvertlng input o~
comparator 36 is connected to a reference voltage VR of, for example, ~0.12 volts DC. Voltage comparator device 9 54,469 LM360 available from National Semiconductor may bs used ~or both pre-~rlgger comparator 35 and zero-crossing comparator 36 .
A voltage signal VF available at an output terminal of pre-trlgger comparator 35 ls input to a clock input terminal o~ pr~-trigger ~lip flop 38. Device 74LS74A
available ~rom Texas Instrum~nts may be used for pre-trlgger flip-flop 38. Both a preset ~erminal and a ~
te~minal of pre-trigger fllp-flop 38 are tied to l5 volts DCo A voltage signal VG available at a Q output of pre-trigger flip-flop ~8 is an input to NA~D gate 40. Device 74LS00 available from Texas Instruments may be used for NAND gate 40. A voltage slgnal VH available at an ouput terminal of zero-crossing comparator 36 is a second input to NAND gate 40.
A voltage signal VI available at an output of NAND gate 40 is input to an ~ input of monostable ~2.
Device 74LS221 available from Texas Instruments may be used for monostable 4~. ~oth a clear input and a B input of monostable 42 are tied ~o +5 volts DC. A voltage signal VK
available at a Q output o mono~table 42 ~s input to a clear termlnal of pre-trlgg~r ~llp~flop 3~. A capacltor 41 is connected in parallel to CEX and RCEX terminal~ o~
monostAble 42 while reslstor 43 i~ connected between ~he RC~X torminal oP monostable 42 and a v~altage source o~ ~5 volts DCo A voltage signal VJ i3 available at a Q output of monostable 42.
In operation, the filtered ihpUt signal VA is input to automatic gain control clrcuitry shown within the dotted lines of FIG. 1 which consists of multiplier 19, invert~ng amplifier 21, peak detector 24, buffers 25 and 29 and error amplifier 26~ The automatic gain control circuitry functions to regulate the amplitude of voltage signal VB at a nominal 10 volt peak-to-peak level.
54,q69 Analy~ls shows that the automatic gain control circuitry exhibits a transfer function which can be represented hy the fol1owing equation: .
IVBI ~ (1 B) VR ~ _ ) ~here IVBI ab~olute value o~ the pea~ value of voltage signal VB;
Al absolute value of the peak value of voltage signal VA;
= dimensionles~ ratio of th~ resistance . values in ohms of resistor 23 to resistor 22;
= dime~sionless ratio of the reslstanoe values i~ ohms of resistor 28 to re~istor 27;
VR a re~erence voltage at th~ noninverting input of error amplifier 2~.
~ y way o~ ~xample o~ the operakion of the automatic gain control circuitry, let ~ 20 anc~ ].et V~
~ ~S volt~ DC~ The ahove equation can be 3impli~ied a~
follow~:
IVal ~ S.2S ~ IVAI
~I--V I , 0 0 2 S J
For IVAI ~ 0.025 VO1tS~ IVBI is vexy nearly equal to 5.~5 volts. For example, if IVAI = 1 volt, then IVBI - 5O122 volts; if IVAI - 10 volts, then IV~7 - SO2369 volts. The preceding example d2monstrates that the amplitude of the voltage VB remains within 2.5~ of $.25 volts for a 10:1 variation in the amplitude of VA.
11 5~,~69 The voltage signal V~ is then bu~ered by device 30 and input to a low-pas ilter to reduce hlgh-Erequency noiseO The resulting voltage signal VE ls illugtrated in FIG. 2A. Voltage signal V~ i8 then compare~ by pre-trigger comparator 35 to a positive reference voltage of, ~or example, +1.2 volts DC. The voltage signal VF at the inverted ouput terminal of pre-trigger comparator 35 corresponds to a logic level "1" when~Yer voltage signal VE
is greater than 1.2 volts. Voltag~ signal VF i5 illustrated in FIG. 2B.
Voltage signal VF s~rves as the clock input to positive-edge triggered flip-flop 38. The ~ inp~t and preset input are both alway~ tied to a loglc "1" level.
When voltag~ signal VF goes "high~" the Q outplu~ o~ flip-flop 38 (voltag~ signal VG) also goes "high." The slight delay between the rising edges of th~se signals corresponds to the propagation delay o~ flip-flop 38. Voltage signal VG is illustrated in ~I~. 2C.
Voltage signal VE i5 also i~put to zero-crossing comparator 36 where lt is compared to a negative reference voltage of, ~or example, -0.12 voltc DC. The voltage signal VH at the output terminal o~ zero-crossing detector 36 corre~ponds to a logic level "1" whenever voltage signal VE is les3 than -0.12 volt~. Voltage signal VN is illustrated in FIG~ ~D.
The voltage ~lgnal VI goes "low" wh-3never both lnputs VG and VH are at the loglc "1" level. Voltage signal V~ i~ illustrated in FIG. 2E~ The falling edge o~
voltage signal VI which is input to the ~ termlnal of monostable 42 causes the Q output of monostable 42 (vcltage signal v,~) to go "high" and th~ Q output (voltage signal VK) to go "low. " The width o~ these signals VJ and VK is approximately equal to .7U secr Thi~ pulse width is ~OC3G~6 12 54,469 determined by the Yalues of capacitor 41 and resistor ~3.
Voltage signals VJ and VK are illustrated in FIG5. 2F and 2G, respectively.
The voltage signal VJ is input to processing circuitry ~not shown) for determining turblne blade vibratlon in a known manner. The voltage signal V~ is input to the c].ear terminal o~ ~lip-10p 38 to cause voltage signal VG to return to a logic "0" level.
The design o ths circuit 10 of the present invention prevents the erratic triggering of the "time of arrival" pulse VJ due to varlatlons in input signal VA
amplitude and the presence of noi~e on the input signal VA.
First, the automatic gain control circuitry prevlously described regulates the amplitude of voltage signal VE at a nominal peak to-peak value. Second, the rising edge of voltage slgnal VH (the ri~ing edge o~ Yoltage signal VH
corresponds to the tlme that voltage signal VE crosses the reference voltage of -0.12 volts when voltage signal VE is decreaslng in value whlch ln turn corresponds to the time at which a turbine blade passes magnetic sensor S0) ls only permitted to trlgger mono~table 42 ln order to produce the pul~e on voltage ignal VJ when voltage signal ~ i9 at a logic "1" level. Voltage slgnal VG goes to a logic "1"
level only when voltage si~nal V~ cro~se~ the ~1~2 volt re~erence axis at a time when voltage ~ignal V~ i9 increasing in valueO Thus~ the clrcuit 10 of the present lnventlon anticipates the tlme when voltage slgnal VE will cross the -0.12 volt re~erenc~ axis in response to a turbine blade passing the magnetlc sensor S0 by first detectlng the positive portion o~ the ~inusoid of voltage signal Y~. Any noise which erratically causes voltage signal YE to cross the -0 . 1 2 Yolt reference axis will not, thus, erroneously produce a pulse on voltage signal VJ and provide incorrect turbine blade "time o axrival" dataO
~62~f~
1 3 5~, 469 The circuit lO of the present inventlon l~ also designed such that its operatlon i not sensitive to the frequency o~ the input slgnal VA. The voltage slgnal V
produced by flip-flop 38 which antlclpates the "tlme of arrival" of a turbine blade at the magnetic sensor 50, is trigg~red when voltage signal VE crosses tha ~1.2 volt reference axis at a time when voltage ~igna} VE i5 increaslng ln Yalue and i9 entlrely lndependent of the frequency of the ~nput signal VA, A sensor 50 which can be used in combination with the circult lo of FIG. 1 is illustrated ln FIG. 3~ The magnetic sensor 50 is a self-generating, vaxiable-reluctance transducer which does not require a power supply. Su~h sensor^q are often used ~or measur1ng rotational speed by counting the teeth on a gear~
Appropriate sensors are commercially available and can be obtained in a variety of con~iguratioQs and package designs for particular appllcations.
The sensors used in combinatlon with the present invention, have, for example, a very high strength magnet 52. The sensor housing 54 may be machlned ~rom a single piece of ~talnless steel bar stock, whlch i9 enclosed by EB
weldlng to special hermetically seale~ connectors 56. The magnet 52 operate~ in con~unction wlth a pole piece 5~. A
pick~up coil 60 pro~uces a signal which i3 conducted hy slgnal wlres to the diP~e~entlal amplif~er 12 o~ FIG. l.
~ The lnternals o~ the sensor 50 should be suitable ~or operation at 550 E (287.8 C). Such sensors can be obtained from Ai~pax, a division vf North American Phillips or Electro-Products. The mountlng o~ sensors, such as sensor 5Q, in a turbomachlne ls well known. See ~or example V.s. Patent No. 4,573,3S8 issued ~arch ~, 1986 to Luongo~ Sensor to surface distances may vary ~etween 15Q
to 250 mils (.0381 to .Q635 mm).
~D06Z86 14 54,~69 Whlle the pre.~ent invention has been described in connectlon with an exemplary embodiment thereof, it will be understood that many modifications and variations will be readily apparent to those of ordinary skill in the art.
This disclosure and the following claims are intended to cover all such modifications and variations.
Claims (17)
1, An apparatus for precisely detecting the passing of an individual blade of a rotating machine past a stationary sensor, comprising:
stationary sensor means for producing an input signal each time the blade passes said sensor means;
automatic gain control means responsive to said sensor means for regulating the amplitude of said input signal;
means responsive to said automatic gain control means for producing an output signal representative of the time at which the blade passes said sensor means.
stationary sensor means for producing an input signal each time the blade passes said sensor means;
automatic gain control means responsive to said sensor means for regulating the amplitude of said input signal;
means responsive to said automatic gain control means for producing an output signal representative of the time at which the blade passes said sensor means.
2. The apparatus of claim 1 wherein said automatic gain control means includes a digital multiplier.
3. The apparatus of claim 2 wherein said automatic gain control means further includes peak detector means for producing a peak detector output signal representative of the amplitude of said input signal.
4. The apparatus of claim 3 wherein said peak detector means includes a comparator.
5. The apparatus of claim 3 wherein said automatic gain control means further includes error amplifier means for producing an error amplifier output signal representative of the difference between said peak detector output signal and an error amplifier reference signal.
6. The apparatus of claim 5 wherein said error amplifier means includes an operational amplifier.
7. The apparatus of claim 1 wherein said stationary sensor means includes magnetic sensors,
8. The apparatus of claim 1 wherein said means responsive to said automatic gain control means includes zero-crossing detection means for producing an output signal each time said input signal crosses a reference axis, means for producing a gating signal coinciding with the expected arrival time of the blade at said sensor means, gate means responsive to said gating signal for conducting said output signal which occurs during the expected arrival time of the blade at said sensor means and means responsive to said conducted output signal for producing a digital pulse coinciding with the time at which the blade passes said sensor means.
9. The apparatus of claim 8 wherein said zero-crossing detection means include a first comparator for receiving said input signal at a first input terminal thereof and for receiving a first reference signal at a second input terminal thereof, said output signal being available at an output terminal thereof.
10. The apparatus of claim 9 wherein said means for producing a gating signal includes a second comparator for receiving said input signal at a first input terminal thereof and for receiving a second reference signal at a second input terminal thereof, said gating signal being available at an output terminal thereof.
11. The apparatus of claim 10 additionally comprising a flip-flop for propagating said gating signal to said gate means until such time as said flip-flop is cleared.
12. The apparatus of claim 11 wherein said gate means includes a digital logic gate.
13. The apparatus of claim 12 wherein said logic gate includes a NAND gate.
14. The apparatus of claim 13 wherein said means for producing a digital pulse includes a monostable vibrator.
15. An apparatus for precisely detecting the passing of an individual blade of a rotating machine past a stationary sensor, comprising:
stationary sensor means for producing an input signal each time the blade passes said sensor means;
automatic gain control means responsive to said sensor means for regulating the amplitude of said input signal;
zero-crossing detection means for producing a digital output signal each time said input signal crosses a reference axis;
means for producing a digital gating signal coinciding with the expected arrival time of the blade at said sensor means;
gate means responsive to said digital gating signal for conducting said digital output signal which occurs during the expected arrival time of the blade at said sensor means; and means responsive to said conducted digital output signal for producing a digital pulse coinciding with the time at which a blade passes said sensor means.
stationary sensor means for producing an input signal each time the blade passes said sensor means;
automatic gain control means responsive to said sensor means for regulating the amplitude of said input signal;
zero-crossing detection means for producing a digital output signal each time said input signal crosses a reference axis;
means for producing a digital gating signal coinciding with the expected arrival time of the blade at said sensor means;
gate means responsive to said digital gating signal for conducting said digital output signal which occurs during the expected arrival time of the blade at said sensor means; and means responsive to said conducted digital output signal for producing a digital pulse coinciding with the time at which a blade passes said sensor means.
16. A method of detecting the passing of an individual blade of a rotating machine past a stationary sensor, comprising the steps of:
producing an input signal each time the blade passes a stationary sensor means;
regulating the amplitude of said input signal;
producing an output signal each time said input signal crosses a reference axis, producing a gating signal coinciding with the expected arrival time of the blade at said sensor means;
selectively conducting said output signal in response to said gating signals; and producing a digital pulse coinciding with the time at which the blade passes said sensor means.
producing an input signal each time the blade passes a stationary sensor means;
regulating the amplitude of said input signal;
producing an output signal each time said input signal crosses a reference axis, producing a gating signal coinciding with the expected arrival time of the blade at said sensor means;
selectively conducting said output signal in response to said gating signals; and producing a digital pulse coinciding with the time at which the blade passes said sensor means.
17. The method of claim 16 wherein the step of producing an input signal includes the step of producing an input signal with a stationary magnetic sensor.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US288,592 | 1988-12-22 | ||
| US07/288,592 US5015949A (en) | 1988-12-22 | 1988-12-22 | Steam turbine blade arrival time processor with automatic gain control |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2006286A1 true CA2006286A1 (en) | 1990-06-22 |
Family
ID=23107784
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002006286A Abandoned CA2006286A1 (en) | 1988-12-22 | 1989-12-21 | Turbine blade arrival time processor |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US5015949A (en) |
| JP (1) | JPH02216018A (en) |
| KR (1) | KR900010377A (en) |
| CN (1) | CN1044855A (en) |
| CA (1) | CA2006286A1 (en) |
| ES (1) | ES2019770A6 (en) |
| IT (1) | IT1236893B (en) |
Families Citing this family (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5148711A (en) * | 1990-11-01 | 1992-09-22 | Westinghouse Electric Corp. | Apparatus and method for removing common mode vibration data from digital turbine blade vibration data |
| US5144233A (en) * | 1991-08-30 | 1992-09-01 | Delco Electronics Corporation | Crankshaft angular position voltage developing apparatus having adaptive control and diode control |
| US5459398A (en) * | 1993-12-17 | 1995-10-17 | Delco Electronics Corporation | Adaptive threshold circuit |
| US5510706A (en) * | 1994-02-22 | 1996-04-23 | Delco Electronics Corporation | Differential to single-ended conversion circuit for a magnetic wheel speed sensor |
| US7170284B2 (en) * | 2002-02-13 | 2007-01-30 | Hood Technology Corporation | Blade detection sensor having an active cooling system |
| US6927567B1 (en) * | 2002-02-13 | 2005-08-09 | Hood Technology Corporation | Passive eddy current blade detection sensor |
| US20070068225A1 (en) | 2005-09-29 | 2007-03-29 | Brown Gregory C | Leak detector for process valve |
| US9000777B2 (en) * | 2005-12-14 | 2015-04-07 | Hamilton Sunstrand | System to measure time of arrival and thickness of rotor blades via microwave energy |
| US7913566B2 (en) * | 2006-05-23 | 2011-03-29 | Rosemount Inc. | Industrial process device utilizing magnetic induction |
| GB0712926D0 (en) * | 2007-07-04 | 2007-08-15 | Qinetiq Ltd | Eddy current sensors |
| US8898036B2 (en) | 2007-08-06 | 2014-11-25 | Rosemount Inc. | Process variable transmitter with acceleration sensor |
| ATE521975T1 (en) * | 2008-02-27 | 2011-09-15 | Ansaldo Energia Spa | METHOD AND DEVICE FOR DETECTING THE NATURAL FREQUENCIES OF VIBRATION OF A TURBINE BLADE |
| US8250924B2 (en) * | 2008-04-22 | 2012-08-28 | Rosemount Inc. | Industrial process device utilizing piezoelectric transducer |
| US7941281B2 (en) * | 2008-12-22 | 2011-05-10 | General Electric Company | System and method for rotor blade health monitoring |
| US7800434B1 (en) * | 2009-04-07 | 2010-09-21 | Micrel, Inc. | Edge detect receiver circuit |
| JP5293406B2 (en) * | 2009-05-28 | 2013-09-18 | 株式会社Ｉｈｉ | Noncontact blade vibration measurement method for rotor blades |
| US8963735B2 (en) | 2011-11-30 | 2015-02-24 | Rosemount Inc. | Turbine meter pre-scaling terminal block electronics |
| KR101440354B1 (en) | 2012-04-16 | 2014-11-03 | 한국에너지기술연구원 | Power Steam Generator by rapid pyrolysis suspension firing using FRDF |
| US9593941B2 (en) | 2014-09-24 | 2017-03-14 | Hood Technology Corporation | Clearance detection system and method using frequency identification |
| CZ2017665A3 (en) * | 2017-10-18 | 2019-01-02 | Ăšstav termomechaniky AV ÄŚR, v. v. i. | Method of identification of ferromagnetic blades of a machine under rotation |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3715659A (en) * | 1970-03-25 | 1973-02-06 | Reliance Electric Co | Inductive non-contact vibration analyzer which is independent of standoff distance |
| US3908167A (en) * | 1974-06-05 | 1975-09-23 | Rca Corp | Exhaust-responsive engine speed and condition indicator |
| US3944936A (en) * | 1974-08-07 | 1976-03-16 | Rca Corporation | Zero crossover detector |
| US3995224A (en) * | 1975-04-30 | 1976-11-30 | Rca Corporation | Fast automatic gain control circuit with adjustable range |
| US4037163A (en) * | 1976-03-08 | 1977-07-19 | General Electric Company | Automatic gain control circuit |
| US4013967A (en) * | 1976-04-29 | 1977-03-22 | The United States Of America As Represented By The Secretary Of The Navy | Mid-pulse detector |
| US4563643A (en) * | 1982-07-30 | 1986-01-07 | Westinghouse Electric Corp. | Eddy current proximity sensor for use in a hostile turbine environment |
| US4518917A (en) * | 1982-08-31 | 1985-05-21 | Westinghouse Electric Corp. | Plural sensor apparatus for monitoring turbine blading with undesired component elimination |
| US4609869A (en) * | 1983-04-13 | 1986-09-02 | Electro Corporation | Magnetic sensor and circuit for detecting the edge of a target as it passes the centerline of the sensor |
| GB8318509D0 (en) * | 1983-07-08 | 1983-08-10 | Rolls Royce | Vibration monitoring in rotary blade machines |
| US4573358A (en) * | 1984-10-22 | 1986-03-04 | Westinghouse Electric Corp. | Turbine blade vibration detection apparatus |
| US4922757A (en) * | 1988-06-13 | 1990-05-08 | Westinghouse Electric Corp. | Apparatus for precise detection of blade passing times in a steam turbine |
-
1988
- 1988-12-22 US US07/288,592 patent/US5015949A/en not_active Expired - Fee Related
-
1989
- 1989-12-18 KR KR1019890018810A patent/KR900010377A/en active IP Right Grant
- 1989-12-19 IT IT02274289A patent/IT1236893B/en active IP Right Grant
- 1989-12-21 CA CA002006286A patent/CA2006286A1/en not_active Abandoned
- 1989-12-21 JP JP1332513A patent/JPH02216018A/en active Pending
- 1989-12-21 ES ES8904317A patent/ES2019770A6/en not_active Expired - Fee Related
- 1989-12-22 CN CN89109450A patent/CN1044855A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| IT1236893B (en) | 1993-04-26 |
| IT8922742A0 (en) | 1989-12-19 |
| ES2019770A6 (en) | 1991-07-01 |
| IT8922742A1 (en) | 1991-06-19 |
| JPH02216018A (en) | 1990-08-28 |
| US5015949A (en) | 1991-05-14 |
| CN1044855A (en) | 1990-08-22 |
| KR900010377A (en) | 1990-07-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |